These combination needle and check valve flow controls are typically used to control air flow from air cylinders, thereby controlling the speed at which the piston strokes, either while extending or retracting, depending on their location in the circuit.
Flow control valves allow free flow from the inlet to the outlet past the needle and check valve. In reverse flow, from the outlet to the inlet, the check valve is sealed and the flow must now pass through the metered passage controlled by the tapered adjustment needle.
